Expression and purification of mIL-21-hIgGFc fusion protein in 293E cells and its effects on CD8+T cell phenotype / 中国免疫学杂志

Objective:To express recombinant protein mIL-21-hIgGFc in 293E cells,and investigate its effect on CD8+T cell.Methods:Total RNA was extracted from the mouse spleen cells ,and then IL-21 gene was amplified by RT-PCR and inserted into expression vector PTT3-hIgGFc.PTT3-mIL-21-hIgGFc were transfected into 293E cells by calcium phosphate method.The supernatants were collected at 48 hours and 72 hours and concentrated by MOLLIPORE Labscale TM TFF system ( 5 kD membrane ).The mIL-21-hIgGFc fusion protein was purified with HiTrap TM Protein G column.The protein was quantified by SDS-PAGE and ELISA.The biological activity of the protein was determined by detecting the change of the phenotypes of CD 8+ T cells treated with the protein.Results: The constructed recombinant plasmid PTT 3-mIL-21-Fc was confirmed by sequencing.PTT3-mIL-21-Fc was transfected into 293E cells,mIL-21-Fc protein in culture supernatant was collected after 48 hours and 72 hours.The protein in cell su-pernatant reached a concentration of 787 ng/ml which was determined by ELISA.The protein was purified by Protein G chromatography column.P1A-specific T cells were treated with mIL-21-hIgGFc, and found that the CD44low CD62Lhi CD8+ population increased compared to the control.Conclusion:We built PTT3-mIL-21-hFc recombinant plasmid, expressed mIL21-hFc fusion protein in 293E cells,and purified by Protein G column.By treating mIL-21-hFc ,the antigen-primed CD8+T cells prefer to differentiate into CD44low CD62Lhi CD8+T cells which had been reported as a memory stem phenotype .This protein may be used to improve the effectness of adoptive T cell cancer therapy.

IL-21 accelerates xenogeneic graft-versus-host disease correlated with increased B-cell proliferation

Graft-versus-host disease (GVHD) is a prevalent and potential complication of hematopoietic stem cell transplantation. An animal model, xenogeneic GVHD (X-GVHD), that mimics accurately the clinical presentation of GVHD would provide a tool for investigating the mechanism involved in disease pathogenesis. Murine models indicated that inhibiting IL-21 signaling was a good therapy to reduce GVHD by impairing T cell functions. We sought to investigate the effect of exogenous human IL-21 on the process of X-GVHD. In this study, human IL-21 was expressed by hydrodynamic gene delivery in BALB/c-Rag2⁻/⁻ IL-2RΓc⁻/⁻ (BRG) immunodeficient mice which were intravenously transplanted human peripheral blood mononuclear cells (hPBMCs). We found that human IL-21 exacerbated X-GVHD and resulted in rapid fatality. As early as 6 days after hPBMCs transplanted to BRG mice, a marked expansion of human CD19⁺ B cells, but not T cells, was observed in spleen of IL-21-treated mice. Compared with control group, IL-21 induced robust immunoglobulin secretion, which was accompanied by increased accumulation of CD19⁺ CD38(high) plasma cells in spleen. In addition, we demonstrated that B-cell depletion was able to ameliorate X-GVHD. These results are the first to find in vivo expansion and differentiation of human B cells in response to IL-21, and reveal a correlation between the expansion of B cells and the exacerbation of xenogeneic GVHD. Our findings show evidence of the involvement of B cells in X-GVHD and may have implications in the treatment of the disease.

The tumor immunosuppressive microenvironment impairs the therapy of anti-HER2/neu antibody

It has been well established that immune surveillance plays critical roles in preventing the occurrence and progression of tumor. More and more evidence in recent years showed the host anti-tumor immune responses also play important roles in the chemotherapy and radiotherapy of cancers. Our previous study found that tumor- targeting therapy of anti-HER2/neu mAb is mediated by CD8(+) T cell responses. However, we found here that enhancement of CD8(+) T cell responses by combination therapy with IL-15R/IL-15 fusion protein or anti-CD40, which are strong stimultors for T cell responses, failed to promote the tumor therapeutic effects of anti-HER2/neu mAb. Analysis of tumor microenviornment showed that tumor tissues were heavily infiltrated with the immunosuppressive macrophages and most tumor infiltrating T cells, especially CD8(+) T cells, expressed high level of inhibitory co-signaling receptor PD-1. These data suggest that tumor microenvironment is dominated by the immunosuppressive strategies, which thwart anti-tumor immune responses. Therefore, the successful tumor therapy should be the removal of inhibitory signals in the tumor microenvironment in combination with other therapeutic strategies.